Multiple-antenna system for radiocommunication



. I 2 March 29,1927. L'ESPENSCHIED I 7 MULTIPLE ANTENNA SYSTEM FOR RADIOCOMMUNICATION Filed Sept, 5. 1921 3 sheets-sheen J J Y i 7a 22 2/ 24 20 I r I l I (Fg4 I; 1 W195) g 25 L 1 1 T F I '3 r 1 l l I l J 1 M l 1/ Q i. (5&2) INVENTOR l flspelzsa/zied Wu 7 k ATTORNEY 1,622,370 March 1927' L. ESPENSCHIED MULTIPLE ANTENNA SYSTEM FOR RADIOCOMMUNICATION Filed Sept, 5. 1921 3 Sheets-Sheet z INVENTOR Li's 0100M I BY ATTORNEY Patented Mar. 29, 1927.

ITED STAT .ATENT "FF'IQE.

LLOYD ESPENSCHIED, or eu'nnns, new Yoaia, AssIc-uvon T0 AMERICAN TELEPHONE AND TELEGRAPH ooMrAi Y, A consort-Arron or NEW YORK.

MULTIPLE-ANTENNA SYSTEM FOR RADIOCOMMUNICATION.

Application filed September The principal object of my invention is to provide means for the unitary operation of a radio antenna array. Another object of my invention is to provide means to operate a plurality of antennae at a central station in proper amplitude relation and phase relation to secure effective conjoint action of these elements. In certain aspects my invention involves multiplex carrier current operation of an antenna array in connection with a central station.

In the accompanying drawings I have shown diagrammatically a specific embodiment of my invention and I now proceed to describe this with the understanding that it is by way of example and that the invention is defined in the appended claims. In these drawings, Figure 1 is a diagram showing. the general arrangement of the apparatus at one multiple antenna station. Fig. 2 is a diagram of the central station apparatus for an antenna array. Fig. 3 is a diagram showing the apparatus associated with a single transmitting antenna. Fig. 4 is a diagram showing the apparatus associated with a single receiving antenna and Fig. 5- is a diagram showing how the transmitting and receiving. antennae may be disposed in an array.

In Fi s. 2, 3 and 4 I have indicated certain elements of apparatus diagrammatically by rectangles with suggestive initials, A for amplifier, F for filter, M for modulator, D for demodulator, T for tuned circuit, 0 for oscillation generator, N for artificial line or network, P for power tube and rp for phase shifter. These elements of apparatus are well known and are describedin various publications, for example in Blackwell & Colpitts, A. I. E. E. paper of April, May and June, 1921.

Referring to Fig. 1, the central station 11 is connected by a pair of conductors 12 with the hybrid transformer secondary 13 from whose middle points 14 a pair of conductors 18 goes to the transmitting antennae. There is a branch 19 for each antenna. 22 and the respective transmitting apparatus is connected to the antenna through a transformer 21.

The receiving" antennae 26 are connected through transformers 25, receiving apparatus 24, and branch conductors 23 to the receiving line 17, which leads to the transformer primary winding 15 associated with 3, 1921. erial N0. 498,187.

the secondary winding 13. The line 12 is balanced by the network or artificial, line 16. The central station ll is shown in Fig. 2. The line 12 and high pass filter 27 are balanced at the central station by the network Orartificial line 29 and between them is the primary winding 28 of a hybrid tran former, whose secondary 30 is connected to a receiving circuit 52. The middle points 31 of the windings 28 are connected through a transformer or repeating coil 32 to the transmitting line 39.

The oscillation generator 33 generates alternating current of a frequency of 5,000 cycles per second. The current of this frequency is delivered to the harmonic producer 34 which acts by distortion to produce currents of higher frequencies, harmonics of the fundamental, all of which are superposed in the output circuit 35. From this output circuit 35, one branch leads through a tuned circuit 86 (tuned to 5,000 cycles per second) and an amplifier 37, then a band filter 38 to the transmitting circuit 39. Other branches from the circuit take off higher frequencies delivered by the harmonic producer 34. One of these branches leads through the tuned. circuit 46, tuned to 15,000 cycles per second, thence through the amplifier 47 to the branch circuits. 48 and 57.

At 40 is an. ordinary sub'scribers telephone set for transmitting and receiving, connected by a line through the hybrid transformer primary 41 to the artificial line or network 42. The transformer secondary 43 is connected by the circuit 44 to the input of the modulator 45. This modulator 45, of the balanced carrier suppression type, receives current of frequency 15,000 through the conductors 48 from the amplifier 47, and the input voice frequency currents over the conductors 44 modulate this 15,000 frequency current and the modulated current is delivered from the modulator to the filter 49, thence to the amplifier 50 and thence through the band filter 51 to the transmitting line 39. The filters 49 and 51 pass the upper side band with respect to the carrier frequency of 15,000.

It is contemplated that all of the radio stations in communication with the one now being described shall have impressed upon them a fundamental frequency determined by the oscillation generator 33. Accordingly such other stations will be like the one now being described, except that they will have the switch 89 thrown to the dotted line position. Among the frequencies received from the distant station in any such case will be 5,000 in the circuit 52, and this will be taken through the filter 53 and amplifier 90 and delivered to the harmonic generator 34.

The received current in the circuit 52 passes in series to the band filter such as 55, and from each of these the current that is passed by such filter goes to a corresponding demodulator 56. The filter 55 passes the upper side band with respect to the carrier frequency 15,000. The particular demodulator designated 56 in Fig. 2 receives current of a frequency 15,000 cycles per second through the conductors 57 and the output current of voice frequency goes through the amplifier 58 and filter 59 to the middle points 61 of the hybrid transformer primary winding 41.

The transmitting apparatus between the line 18 of Fig. 1 and the individual transmitting antenna 22 is shown in Fig. 3. The branch conductors 19 from the transmitting line 18 receive the currents of frequency 5,000 and the upper side band based on 10,000, 15,000, etc, as modulated by the re spective voice currents. All these superposed currents go through the band filter 62, the repeating coil or transformer 63, and amplifier 64lto the filter 67, which connects with the modulator 7 3, In series with filter 67 is the primary of a transformer 66 whose secondary isconnected through a filter 60 which passes 5,000 frequency to the input of the harmonic distorter 67, from which the output goes through the rheostat or potentiometer 68 to the filter 91 which passes frequency 50,000 through the amplifier 69 to the power tube 70. he 50,000 frequency output from power tube 70 goes through the phase shifter 71, and by means of the trans former 72 this output is put in series in the output side of the filter 67. Thus the modulator 73.1nodulates the current of 50,000 frequency from the phase shifter 71 by means of the current belonging to the upper side bands of frequencies based on 10,000, 15,000, etc, which come through the filter 67. The modulated output current from the modu lator 7 3 goes through the transformer 7 4 and through the band filter 75, and transformer 21 to antenna 22. This band filter 7 passes frequencies greater than 50,000 and less than 80,000 cycles, comprising the upper side band of the modulator 73.

Referring to Fig. i, the receiving antenna 26 is connected through the filter 86, amplifier and transformer 84 to the demodulator 77. The branch circuit 78 from the trans mitting circuit 18 leads through the filter 79 which passes only current of the fundamental frequency 5,000. This is amplified in the amplifier 80 and delivered to the distorter 81, thence through the filter 87, which passes current of frequency 50,000 to the phase shifter 82 from which the current is impressed by means of the transformer 83 on the demodulator 77 which receives the filtered and amplified current through the transformer 84: from the receiving antenna 26. The demodulated output current from the device 77 goes through the filter 76 to the line 17.

The system heretofore describedis adapted to deliver currents in any desired proper relation of amplitude and phase to the re spective antennae of a transmitting array, such as the antennae 22, which may be arranged as shown in Fig. 5. The system is also adapted to receive currents over the receiving antenna: 26, which may be arranged as shown in Fig. 5 and deliver current to the central station in proper amplitude relation and phase relation based on the current received in the antennae 26.

Voice currents coming from the telephone station go through the hybrid coil transformer a1 l3, the secondary circuit as and modulator where they modulate the currents of frequency 15,000 received from the amplifier 47. The filters 49 and 51 pass the upper side band, that is, the currents of a frequency range from 15,200 up to 18,000 which includes the highest essential voice frequency. These currents go over the circuit 39 to the points 31, then through the high-pass filter 27 tothe line 12. Other side bands lying in other frequency ranges may be impressed similarly and at the same time from other input branches upon the circuit 39 and thence upon the circuit 12.

All these carrier currents in the circuit 12 are delivered through the midpoints 14 of the hybrid transformer 13.15, to the circuit 18 connected with which are the branches 19. The particular branch designated 19 in Fig. 3 has its hand filter 62 tuned to take all the frequency side bands desired to be transmitted over circuit 12. In the apparatus shown in Fig. 3 a basic carrier frequency Ill) of 50,000 cycles per second is developed and this is modulated by the complex current received from the circuit 18 and the side band based on the carrier current 50,000 is radiated from the antennae 22.

Each antenna is given the proper amplitude of current in relation to that of other antennae by means of the rheostat 68, and the proper phase relation by means of the phase adjuster 71.

Such a complex current as has been dc scribed as radiated from the antennae 22 may be received'on the antennae 26. The apparatus shown in Fig. icombines this com plex current with a basic frequency of 50,000 cycles per second and demodulates it, giving output currents lying in the various upper side bands of frequency from 3,000 to neaaavo 30,000. These are superposed on the receiving circuit 17 and delivered over the apparatus described to. the circuit 52*. The hand filters 55 are selective tothe respective side bands involved. For example, the filter designated 55 in Fig. 2 passes the side band lymg between 15,200 and 18,000 which in cludes the highest essential voice frequency. This. side band of current is combined the demodulator 5'6 with current of basic frequency 15,000 and the resulting output current of simple voice fi'equency is amplified in the amplifier 5B and goes over the telephone line to the subscribers set 40 It will be understood that it is practically diflicult to transmit over wires of any considerable length currents of a proper frequency to be radiated. from or received by the antennae. Hence it will be seen that my system provides for working with moderate frequencies on the lines 12, 39 and 52, but using these currents of a moderate frequency to modulate currents of much higher frequency for transmitting, or to obtain such moderate frequency currents by demodulation from high frequency received currents.

For the operation of an antenna array it is essential that the currents in the respective antennae and at the central station shall have a precise phase relation and in certain antenna arrays it is moreover desirable that there should be a graded amplitude relation among the currents. It Will be seen that I have accomplished these ends by basing all the currents on a single oscillation generator of frequency 5,000 cycles per second in the particular case described. All of the carrier current-s can be made to have a definite frequency ratio thereto and a definite phase relation so that all parts of the system can be kept in step for effective concurrent operation.

By means of antenna arrays it is known to be practicable to attain high selectivity of transmission or receiving in a particular direction; but to accomplish this purpose it is essential that the proper phase and amplitude relations should be secured as I have just stated, and my system is adapted for that purpose.

I claim:

1. A plurality of antennae assembled to constitute an array for directional operation, a low frequency central station, low frequency conductors extending therefrom to the respective antennae of the array, frequency changing means at the respective antennae for co-operation between said low frequency conductors and said antennae operating at high frequency, and means to adjust the currents for phase and amplitude ateach of the antennae.

2. A plurality of transmitting antennae assembled in orderly arrangement to constitute an array for unitary directional transmission, a plurality of receiving antennae assembled in orderly arrangement toconstitute anantenna array for unitary direction-a1 reception, high frequency modulators at the transmitting antennae adapted todeliver their output currents to said antennae, high frequencydemodulators at the receiving antennae, and low frequency central station operativelyconnected for transmission to all said transmitting antennae and for reception to all saidreceiving antennae.

A multiple antenna directional transmitting array, a multiple antenna direction-at receiving array, a central station connected to all the antennae of both arrays, and means at each antenna to generate carrier currents and to. modulate themfor sending at the transmitting antennae and to. apply them fordemodulation at the receiving antennae.

4. A plurality of antennae constituting a unitary co-ordinate array for directional transmission, a central station, means to generate several carrier currents at the central station, means to modulate them at the central station with currents of signaling frequency, circuits to transmit them thence to the antennae, means controlled over such circuits from the central station to generate radio frequency currents at the respective antennae, means at the antennae to modulate such radio frequency currents by the once modulated currents from the central station, and means to apply the modulatedradio frequency currents to be radiated from theantennae.

5. A plurality of antennae constituting a unitary co-ordinate array for directional reception, a central station, a circuit connecting said antennae and said station, means to receive multiplex modulated radio frequency carrier currents at the antennae, means there to demodulate them and to deliver modulated loW frequency carrier currents over said circuit to said station, means at the station to separate and demodulate such currents and deliver demodulated signal currents, and respective indicators therefor.

6. A plurality of antennae, part of them constituting a unitary co-ordinate array for directional transmission and part of them constituting a similar array for reception, a low frequency central station, low frequency conductive means connecting said central station with said antennae, and apparatus at each antenna operatively connecting it with said conductive means for high frequency operation of the antenna and low frequency operation of the said conductive means.

7 A plurality of antennae, part of them constituting a unitary co-ordinate array for directional transmission and part of them constituting a similar array for reception, a low frequency central station, low frequency conductive means connecting said central stalift) tion with said antennae, apparatus ateach antenna operatively connecting it With said conductive means for high frequency opera tion of the antenna and low frequency operation of the said conductive means, and phase shifting and amplitude adjusting means at each antenna by which their co-ordinate operation for directivity may be secured.

8. A plurality of antennae constituting a unitary co-ordinate array for directional transmission and reception, a central station, means to generate several carrier currents at the central station, means to modulate them at the central station with currents of signaling frequency, a circuit to transmit them thence to the antennae, means controlled over such circuits from the central station to generate radio frequency currents at the antennae, means at the antennae to modulate such radio frequency currents by the once modulated currents from the central station, meansto apply the modulated radio frequency currents to be radiated from the transmitting antennae, means also at the antennae to apply the said generated radio frequency currents to demodulate received modulated high frequency currents on the receiving antennae and deliver modulated low frequency carrier currents to said central station, and means at the station to separate and demodulate such currents and deliver demodulated signal currents, and respective indicators therefor.

In testimony whereof, I have signed my name to this specification this 80th day of August, 1921. a

LLOYD nsrnasonrnn, 

